schlossberg - lasers and optics - spring review 2012
DESCRIPTION
Dr. Howard Schlossberg presents and overview of his program - Lasers and Optics - at the AFOSR Spring Review 2012.TRANSCRIPT
1 DISTRIBUTION A: Approved for public release; distribution is unlimited. 9 March 2012
Integrity Service Excellence
Howard Schlossberg
Program Manager
AFOSR/RSE
Air Force Research Laboratory
Lasers and Optics
07 MAR 2012
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2012 AFOSR SPRING REVIEW 2301A PORTFOLIO OVERVIEW
NAME: Dr. Howard Schlossberg
BRIEF DESCRIPTION OF PORTFOLIO:
RESEARCH IN LASERS, OPTICS, AND THEIR APPLICATIONS
LIST SUB-AREAS IN PORTFOLIO:
- LASERS
- NON-LINEAR OPTICS
- LASER-MATTER INTERACTIONS
- MICRO-SYSTEMS
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Anthony E. Siegman 1931 - 2011
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Anthony E. Siegman 1931 - 2011
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Anthony E. Siegman 1931 - 2011
•Invention of Unstable Resonator – 1965
•Keeper of the Modes
•Invention of M2 - 1990
•Ultrashort Pulse Measurements
Tony Wrote the Book on
Lasers
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LASERS
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• High Average Power Solid-State Lasers • Ceramic Laser Solid-State Materials
• Fiber Lasers
• Thin Disk Semiconductor Lasers
• X-PALS
• Modest Power Lasers • Mid-Infrared Semiconductor Lasers
• Mid-Infrared Fiber Lasers
• Nonlinear Optics • Nonlinear Frequency Conversion
• Ultrashort Pulses
• Extreme Light
• High Harmonic Generation
• Mid-and Long Wave Frequency Combs
• X-Ray Imaging
• Micromachining
• Microplasma Arrays • Specialized Lighting
• Plasma chemistry
• Plasma transistor
• RF modulation, protection (DARPA)
Portfolio Summary (Detail)
To Dr. Parra
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• Ceramic Solid-State Laser Materials • Spatially Varying Index and Doping Concentration
• Non-Isotropic hosts
• Fiber Lasers
• Ultra-short, Ultra-Intense Pulses • Matter Interactions, Propagation, X-Ray Beams
• Integrate with HPL JTO Programs
AFOSR Study of 6.1 Opportunities in High
Energy and High Power Lasers
High Energy Solid-State, and Some Gas, Lasers Today
are an Exercise in Mode Conversion
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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Ceramic laser gain media offer a number of important
advantages over single crystals and glasses
:
• Ceramic media can be fabricated with arbitrary shapes and size.
• Ceramics are well suited to produce composite gain media,
consisting e.g. of parts with different doping levels, or even different
dopants
• Spatially varying doping profiles are relatively easily possible. These
aspects give additional freedom in laser design.
• Significantly higher doping concentration can be achieved without
quenching effects degrading the laser efficiency.
• Some materials, e.g. sesquioxides are very difficult to grow into
single crystals, and much easier to obtain in ceramic form.
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Ceramic Solid-State Laser Materials
Program Examples
• Ikesue (JTO, Dr. Caster) – Processing, diagnostics
– Navy does characterization, lasing (Shori)
• Ballato - Clemson (JTO, Dr Sayir)
– Sesquioxides
• Byer – Stanford (JTO, AFOSR)
– Nd, Yb, Tm doped ceramics, Tm fibers
– Works with U. Central Florida (Gaume)
• Wu – Alfred University (AFOSR YIP)
– Yb doped Sr5(PO4)3F (Yb:S-FAP)
• Excellent properties as laser host
• Prototype uniaxial material
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AFOSR Sponsored Ceramic Research Meeting in Nagoya
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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There is no requirement that the
pumping frequency be much higher
than the frequency emitted as long as
the difference in frequency is much
greater than kT/h, which can assure
the possibility of negative
temperatures.
Schawlow and Townes, Phys. Rev.
112, 1940 (1958).
DPALS (Cesium)
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4 5 6 6 7
0
1
10
12
14
62P
62S
X2
En
erg
y (
10
3 c
m-1
)
Interatomic Distance (Å)
B2
Cs-Ar
Continuous tunability between 4, 3, and 2 level systems
XPALS SYSTEM: Cs-Ar
~837 nm 852.1 nm
Δε
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• The extracted decay constants from laser
excitation spectra yield transition region
slope of -3/2 kT
• ~0.7 kT is a critical value of the energy
separation between adjacent laser levels
• 4 level laser system collapses in a kT
interval of ~ 2 meV
XPALS SUMMARY
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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PHOTONIC BANDGAP GAS LASERS
•Diode-pumped gas laser
•Long interaction length allows small absorption
•Enhanced efficiency possible through V-V collisions
•Large mode area or coherent coupling possible •Corwin - Kansas State U
• U. New Mexico
•University of Bath
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3.113 3.114 3.1150
100
200
300
400
500
600
3.171 3.172 3.173
Sp
ectr
al In
ten
sit
y (
arb
. u
nit
s)
Wavelength (m)
Actual Wavelengths:
3114.6 nm, R(11)
3172.4 nm, P(13)
C2H2 Pressure = 111 torr
Herman, J. Chem. Ref. Data 32, (2003).
C2H2 Laser Spectrum and Transitions
C H C H
C H C H
ν1
ν3
v1+v3
00000
Energy states
v4
v5
v2
v3
v1
~1.5
m
~ 3
.8
m
8 m
13 m
~ 3
.1
m
~ 3
.8
m
1.7 m
Potential Lasing States
Vibrational ground state
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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T. Carmon, Univ. Michigan Objective: Continuous-in-Time Micro-Emitter at the Extreme UV
Concept:
1) Nonlinear medium
Xenon gas
2) Optical Enhancement by
IR recirculating in a micro-resonator
Local enhancement by metal (Orange)
Compact cw telecom source, no meter-scaled pulsed lasers
3) Indications for High Harmonics
UV detection with an optical spectrum analyzer
Free Electron detection via current monitoring between electrodes
XUV - e
Xe +
UV
- e
Xe +
- e
Xe + Xe +
Compact CW IR
Laser pump
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Tal Carmon, Univ. Michigan Accomplishments: continuous 4th-Harmonic Generation
Experimentally Demonstrated:
–UV 4th-harmonic generation [Opt. Exp. 2011]
– Laser emission with incoherent pumping [Adv. Mater. 2011]
–HyperRaman emission (two-photon-excited analog of Raman) [Appl. Phys. Lett. 2012, accepted]
•Theoretically analyzed:
–An atom-plasmon-resonator system [New J. Phys., To be submitted]
UV Extreme UV
Th
is y
ea
r
3rd Harmonics & 3rd-order sum-frequency
generation (separately measured during
different experiments, Nature Phys. 2007)
Papers are in collaboration with Cohen, Bartal (Technion), Jarrahi (U of M), Rotschild & Baldo (MIT)
Past
resu
lts
Continuous-in-time pump, 2nd-, 3rd-, & 4th-
harmonics emission. Opt. Exp. 2011
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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• Pulse synthesis with wavelength and coherent beam combining integrated into single setup
– Wavelength beam combining controls frequencies
– Coherent beam combining is implemented with feedback from single-phase sensitive metric
• Advantages
– Scalability
– Reconfigurability
– Large pulse energies, high repetition rates, short optical pulses
– Pulse generation in laser systems, or spectral regions where difficult
Laser Locking for Short Pulse Generation
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Laser Locking
• Feedback is based on single phase sensitive metric
– Allows control of large arrays!
• Stochastic parallel gradient descent algorithm is used for feedback
– Determine performance metric and apply random changes to all inputs
– Update parameters with stochastic gradient
– Vary current to laser arrays to cause phase shift from thermally induced index of refraction change
n
j
nn
j
n
j
n
j uJuu 1
Individual phase Single metric
measurement measurement
Feedback
f1, fc
f2, fc
fn, fc
f1 f2fn
Feedback
f1, fc
f2, fc
fn, fc
J(f1 f2…fn)
This work
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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Dual-comb FT spectroscopy
GaSe
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AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography
(OCT)
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Optical Coherence Tomography (OCT)
• Invented with AFOSR funding
• Very broad-based optical diagnostic technique.
• Expanded under program to include Doppler and polarization- sensitive OCT.
• Recent breakthroughs in speed – spectral and swept source OCT – and resolution.
• Military examples: – Burn depth measurement. – Blood flow. – Airway damage.
• Civilian spin-off examples: – Eye problems. – Coronary artery disease – Barrett’s Esophagus.
• Over 16 million eye diagnostics in 2010
• Over 50 thousand coronary artery
procedures to date
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Problem: High mortality from smoke
Inhalation Injury
• 27% of Army burn admissions suffer inhalation injuries
• 10 times greater mortality than other burn patients
• No technology for early diagnosis
Solution: OCT imaging enables early detection
Status: Clinical trials proposed for USAISR & BAMC
Airway - normal
Inflammation following smoke
inhalation
Advances in speed of OCT imaging and
unique optical probe design enables high
resolution 3D airway imaging
Intracoronary OCT Artery Wall
Lipid
Calcium
Macrophages
Stent
3D OCT of Human Coronary Artery in vivo
• Next major intracoronary imaging modality
• Identifies plaques before heart attack
• Guide stent intervention
• 3 major companies
• Over 50,000 patients imaged
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Thank you